mehavey wrote: I'm having a real problem here. ½mv² exiting the muzzle -- which is necessary to stop the TrulyTrulyBadGuy -- can't be violated to be gentle to the SensitiveGoodGuy.

You're either going to throw an effective load of buckshot -- enough of it/going fast enough -- to get the job done or you're not.

So I'm not going recommend anything reduced-recoil.
Instead I suggest taking the standard 2¾ 00 Buck out...
...and get used to it.

Some people can't take the recoil for a variety of reasons. Some people can't make a follow up well due to recoil. That said: 9 53 gr. pellets moving 1150 fps can make 9 33 caliber wound paths delivering 156 ft. lbs each deliver 1404 total ft. lbs of muzzle energy. I don't know too many people who are going to volunteer to be the Test Dummy for that.